WATCH: Obama says US will do "everything we can" to make Syria ceasefire succeed

The US president remains skeptical that the cessation will hold

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US President Barack Obama hold press conference | Image via @WhiteHouse video on Twitter

Updated 21.50:

US President Barack Obama says the US will do everything it can to make a truce in Syria succeed, despite significant concerns over whether the agreement will hold.

The United States, Russia and other parties have agreed to a pause in hostilities in the country which is due to begin later.

More than a quarter of a million people have died since violence broke out in Syria in 2011, and an estimated 13.5 million people are in need of aid.

Speaking in Jordan earlier this week, the US Secretary of State John Kerry said: "Through the efforts of the International Syria Support Group, the Humanitarian Task Force, more areas will now receive help in the coming days and weeks".

"And that process is being regularised. This access is specifically called for in UN Resolution 2254, and we intend to see that this aid continues to flow".

"The modalities for a cessation of hostilities are now being completed. In fact, we are close to a ceasefire today than we have been", he added.

While Mr Obama says maintaining the deal would depend on a number of factors.

Tonight the United Nations Security Council endorsed the cessation of violence.

The United States ambassador to the UN is Samantha Power: